diff --git a/backend/models.py b/backend/models.py
index 20d54e9..f6b3688 100644
--- a/backend/models.py
+++ b/backend/models.py
@@ -78,6 +78,13 @@ class TradeDirection(str, PyEnum):
     SELL = "sell"  # User sells BTC, gets EUR
 
 
+class BitcoinTransferMethod(str, PyEnum):
+    """Bitcoin transfer method for exchange trades."""
+
+    ONCHAIN = "onchain"
+    LIGHTNING = "lightning"
+
+
 # Role name constants
 ROLE_ADMIN = "admin"
 ROLE_REGULAR = "regular"